An aircraft ejector rack is a device used to carry and release stores such as bombs and missiles from an aircraft in flight. These racks are typically mounted to the undersurfaces of aircraft wings and fuselages and incorporate both release and ejection features. The release features normally include bails or hooks from which stores may be suspended, and the ejection features normally include pneumatically operated rams for forcibly ejecting stores away from the aircraft to minimize the possibility of their colliding with the aircraft after release.
A contemporary ejection rack system of the type described above incorporates an onboard pressurization capability, employing a single pressurization system capable of operating multiple release mechanisms and uses air to operate both the store release bails and ejector rams. The system also includes a miniature compressor and a gas purification system which filters, dries, and stores ambient air as an energy medium. With the onboard compressor, pressure in the system can be maintained at the desired operating level regardless of system usage or temperature changes in the gas. The use of air eliminates the problems associated with the use of pyrotechnics to generate high pressure gasses, such as periodic cleaning required by the corrosives and moisture generated in such systems, and also eliminates the sealing problems commonly found in hydraulically operated ejector racks. An example of such a state-of-the-art pneumatically operated ejector rack system is seen in U.S. Pat. No. 5,583,312.
It has also been found to be desirable to apply differential forces to a store upon release from an aircraft in order to impart a predetermined pitch rate to it. By doing so, the store can be directed upon a flight path which will carry it away from the aircraft so as to minimize the possibility of a store colliding with the aircraft after release. In prior pneumatic systems, such pitch rate control has been accomplished by varying the flow rate and pressure of the fluid supplied to the thrusters. Among the means employed to vary pressure among a group of thrusters have been replaceable orifices of varying cross sectional areas and adjustable orifices disposed in the manifolding between the pressure source and the thrusters. A typical example of an adjustable orifice is shown in U.S. Pat. No. 6,009,788, which will be described in greater detail below. A significant advantage of this particular variable orifice design is that it permits adjustment without disassembling of the ejector system and eliminates the necessity of maintaining an inventory of replaceable orifices. One problem that has been encountered with this system, however, is that in operation the variable orifices assembly tended to leak, making calibration of the device difficult.
Accordingly, there is an unmet need in the art for a pneumatically operated ejector rack including a thruster actuation system having a plurality of improved adjustable flow restricting devices for supplying differential fluid pressure to the thrusters.